Actus et Potentia, a technical expression in sch lastie phraseology.
I.—The terms actus and potentia were used by the scholastics to translate Aristotle's épyea or évrehéxaa, and Gdvrauss. There is no single word in English that would be an exact rendering of either. Act, action, actuality, perfection, determination express the various meanings of actus; potency, potentiality, power, capacity, those of potentia. In general, potentia means an aptitude to change, to act or to be acted upon, to give or to receive some new determination. Actus means the fulfilment of such a capacity. So, potentia always refers to something future, which at present exists only as a germ to be evolved; actus denotes the corresponding complete reality. In a word, potentia is the determinable being, and actus, the determined being. The term actus, therefore, has a much greater extension than act or operation. Every operation is an actus, because it is the complement of a power; but all other perfections and determinations, whatever be their nature, are also actus. On the other hand, the being in potentiâ is not to be identified with the possible being. The latter belongs to the logical order; it is a notion whose elements involve no contradiction. The former belongs to the real order; it exists in a subject which, though undetermined, is capable of determination. Potentia is more than a mere statement of futurity, which has reference to time only; it implies a positive aptitude to be realized in the future. It would also be a mistake to identify the scholastic actus and potentia with the actual and potential energy of physics. These terms apply only to material substances, and are exclusively dynamic; they signify the capacity for doing work, or the actual performing of work. The scholastic terms apply to all, even spiritual, beings, and refer to any reality which they possess or can acquire. The Aristotelian “energy” (actus) as such, 1 e., considered as actuality, can never be potential, these two terms being opposed to each other. Actuality and potentiality are mutually exclusive, since one means the presence, and the other the absence, of the same determination. Yet, in all beings except God (see ACTUS Purus) there is a combination of actuality and potentiality; they possess some determinations and are capable of acquiring others. Moreover, the same reality may be considered as actuality or potentiality, according as we take a retrospective or a prospective point of view. In man, skill and science are actualities if we compare them to human nature, which they pre and in potentia with regard to the same determination.
Aristotle and St. Thomas explain this theory by many illustrations, one of which will suffice. The statue exists potentially in the block of marble, because marble has an aptitude to receive the shape of a statue. This aptitude is something real in the marble, since many other substances are deprived of it. It is a receptive potentiality. With regard to the same statue, the sculptor has the power, by his action, to carve the marble into the form of a statue. His is an active power, a real skill or ability which is lacking in many other persons. In order to have the actual statue (actus). it is necessary for the sculptor to exercise (actus) his real skill (potentia) on a substance which is not yet a statue, but which has a real aptitude (potentia) to become one. I can form no idea either of the marble’s potentiality or of the sculptors skill unless I first know what meant by an actual statue. In the same manner, the man born blind is unable to understand what is meant by the faculty of vision. In general. potentia has no meaning, and cannot be defined except the corresponding actus.
Ii—The distinction between potentia and actus is at the basis of, and pervades, the whole scholastic system of philosophy and theology. Whatever is determinable is considered as potential with regard to the actual determination. Genus and species, subject and predicate, quantity and shape, child and adult, matter and form of the sacraments, etc.. are examples of potentiality and actuality. Here we must confine ourselves to the fundamental applications in metaphysics and im psychology. (1) In Metaphysics the distinction runs through the ten Aristotelian categories. All being. whether substance or accident (q. v.), is either in actu or in ia. The essence of creatures is a potentiality with regard to their existence. Material substances are composed of primary matter and substantial form (see Matter and Form x), matier being a pure ~~ potentiality, i. e., wholly undetermined, and form being the first determination given to matter. Efficient causality is also an application of potentiality and actuality; the cause, when at rest, remains able to act. is a transition from the state of potentiality to that of actuality. Generation, growth, and evolution suppose a capacity which becomes fulfilled. (2) In psychology special emphasis is laid on the reality of the poteniiz, or faculties (q. v-), and their distinction both from the soul and from their operations. External senses are determined or actualized by an external stimulus (see Species), which gives them the determination necessary to act of perception. The internal senses (sensus communis, phantasia, memoria, aestimativa) depend . external sensations for their exercise. Memory and imagination preserve in potentiâ traces of past impressions, and when the proper conditions are ed the image becomes actual. We have no e is a tendency today: in nearly all the sciences s “actuality” ano But, if analyzed y, such theories will necessarily yield potential Tn all things we find capacities for further and evolution, forces and aptitudes - . to terminology these are now real, but not actual They exist only as potentia, which, to manifest themselves, await the proper actualization.
Aristotle, passim, esp. Meaphysics, Vill (Bein a 1331); Sr. Tzomss, Comment in bb. IX Metaphys. (VII Berim ed. ther we a Bavprs, L’ace 4 la puissance dans Arisiote m Rerue thomiste, VII (1899), 40, 153, 274, 584, Vill (1900), 273; W.z1sos, The Metaphysic of Aristotle, Tl, IV; Potential and Actual Reality, in Philosophical Review, VII (1898), 337; Loess, The Arisisiclian, Concept of Gtets, m Philosophical Review, Vi 1897), 18; p= Vorexs, L’acde 4 la pwissence, m Annales de philozopiae chretienne, pn. =, XIV (1886), 471; Bocrzocx m
C. A.
C. A. Dubray.